Cisco Systems Cisco 12008 manual Synchronous Optical Network Connection Guidelines

Site Wiring Guidelines

Synchronous Optical Network Connection Guidelines

The Synchronous Optical Network (SONET) specification for fiber-optic transmission defines two types of fiber:

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Single mode

Multimode

Data transmission in either mode occurs by means of bundles of light rays that enter the fiber at a particular angle.

Single-mode fiber allows only one mode of light to propagate through the fiber; multimode fiber allows multiple modes of light to propagate through the fiber.

Multiple modes of light propagating through the fiber travel different distances, depending on entry angles, causing the light to arrive at destinations at different times. This phenomenon is called modal dispersion.

Single-mode fiber provides higher-bandwidth transmission and supports greater cable distances than multimode fiber. Table 2-3 lists the maximum distances for single-mode and multimode fiber-optic transmissions, as defined by SONET.

If the distance between two connected stations is greater than the maximum distance specified in Table 2-3, significant signal loss can result, making fiber-optic transmission unreliable.

Table 2-3 SONET Maximum Fiber-Optic Transmission Distances

Transceiver Type	Maximum Distance between Stations1
Single-mode	Up to 9 miles (14.5 km)
Multimode	Up to 1.5 miles (2.4 km)

1.Typical results; you should use the power budget calculations to determine the actual distances.

Preparing for Installation 2-21